Documentation

packageNameMap creates a map from a package name to all the versions of that package
NOTE: Provides are not included in the map
NOTE: the sort order is random -- this is perhaps a bug
see also: addProvides

addProvides finds packages that Provide other packages and adds
them to the PackageNameMap. They will be adde to the end of the
list, so that real packages have 'higher priority' than virtual
packages.
NOTE: Does not check for duplication or multiple use